136 UNIVALVES. SERPULA. 



sands: it sometimes attains the extraordinary size of 

 three feet. 



To this same class belongs the well known but rare 

 shell, the watering-pot Serpula, (S. aquaria). Its larger 

 end is closed by a convex disk, with numerous small per- 

 forations, and generally a longitudinal one in the middle, 

 the whole encircled by a dilated margin of elegant papy- 

 raceous tubes, resembling a beautifully plaited ruff or 

 frill J the smaller end is open. It is found in the Indian 

 ocean, and seldom exceeds five inches in length. 



The S. gigantea is about an inch in diameter, and 

 sometimes exceeds half a foot in length. The S. lumbri- 

 calis is a flexuous shell, with a spiral acute tip, and very 

 much resembles a cork-screw. The S. filograna is 

 branched and complicated, and is adorned with a beauti- 

 ful kind of net work, 



One of the remarkable species of this genus is the S. 

 anguina, which has a slit or long-jointed cleft, along the 

 spiral convolutions of its shell. The S. echinata has its 

 shell beset with a succession of spines or prickles; it is 

 usually of a rosy or pink color, and sometimes has its aper- 

 ture margined. 



The S. cornucopias, or horn of plenty, is, in all proba- 

 bility, only a dropped Helix hortensis, or common garden 

 snail, and of course not belonging to this genus. TheS. 

 infundibulum appears as if its first bend was composed of 

 five funnels, inserted within each other. The S. denti-^ 

 culata is sometimes found in the Lepastintinnabulum; and 

 the S. sulcata adheres to the roots of the fucus digitatus. 

 The S. lagena is exactly like an oil-fliask, and the S. re- 

 tori a is retort shaped ; the latter is scarce. The S. incur- 

 vata something resembles the Nautilus semilituus, but it 

 wants the internal concamerated structure. The S. nau- 



